Add a landmine to clobber broken GN bots.

GN bots are having trouble picking up the changes to the resouce ID
range, which was changed in https://codereview.chromium.org/734243003/.

BUG=444902
R=eroman@chromium.org, thakis@chromium.org

Review URL: https://codereview.chromium.org/821303002

Cr-Commit-Position: refs/heads/master@{#309588}

build/get_landmines.py

@@ -63,6 +63,7 @@ def print_landmines():
     print 'Clobber to delete incompatible object binary format with NDK r10c'
   print 'Clobber to fix missing NaCl gyp dependencies (crbug.com/427427).'
   print 'Another clobber for missing NaCl gyp deps (crbug.com/427427).'
+  print 'Clobber to fix GN not picking up increased ID range (crbug.com/444902)'
 
 
 def main():